Adsor����o de CO2 em peneiras moleculares micro e mesoporosas

Microporous molecular sieves of type Y, Beta, ZSM-5, ZSM-12 and ZSM-35, and mesoporous molecular sieves of type MCM-41 and MCM-48, and these sieves modified with triethanolamine and ethylenediamine were obtained and characterized by XRD, FTIR, TGA and nitrogen adsorption. The adsorption tests were performed by the gravimetric method under a stream of CO2 at ambient temperature and pressure. The adsorbents studied showed maximum adsorption capacity of carbon dioxide in the range of 13.1 to 85.5 mg of CO2 per gram of adsorbent.

SYNGAS PRODUCTION FROM CO2-REFORMING OF CH4 OVER SOL-GEL SYNTHESIZED Ni-Co/Al2O3-MgO-ZrO2 NANOCATALYST: EFFECT OF ZrO2 PRECURSOR ON CATALYST PROPERTIES AND PERFORMANCE

Ni-Co/Al2O3-MgO-ZrO2 nanocatalyst with utilization of two different zirconia precursors, namely, zirconyl nitrate hydrate (ZNH) and zirconyl nitrate solution (ZNS), was synthesized via the sol-gel method. The physiochemical properties of nanocatalysts were characterized by XRD, FESEM, EDX, BET and FTIR analyses and employed for syngas production from CO2-reforming of CH4. XRD patterns, exhibiting proper crystalline structure and homogeneous dispersion of active phase for the nanocatalyst ZNS precursor employed (NCAMZ-ZNS). FESEM and BET results of NCAMZ-ZNS presented more uniform morphology and smaller particle size and consequently higher surface areas. In addition, average particle size of NCAMZ-ZNS was 15.7 nm, which is close to the critical size for Ni-Co catalysts to avoid carbon formation. Moreover, FESEM analysis indicated both prepared samples were nanoscale. EDX analysis confirmed the existence of various elements used and also supported the statements made in the XRD and FESEM analyses regarding dispersion. Based on the excellent physiochemical properties, NCAMZ-ZNS exhibited the best reactant conversion across all of the evaluated temperatures, e.g. CH4 and CO2 conversions were 97.2 and 99% at 850 ºC, respectively. Furthermore, NCAMZ-ZNS demonstrated a stable yield with H2/CO close to unit value during the 1440 min stability test.

Thermal behaviour studies of solid state compounds of cinnamylidenepyruvate with trivalent lanthanides and yttrium (III) in an atmosphere of CO2

Solid state cinnamylidenepyruvate of trivalent lanthanides (except for promethium) and yttrium, were prepared. Thermogravimetry, derivative thermogravimetry (TG, DTG), differential scanning calorimetry (DSC), X-ray diffraction powder patterns and complexometry were used to characterize and to study the thermal behavior of these compounds in a dynamic CO2 atmosphere. The results obtained showed significative differences on the thermal stability and thermal decomposition of these compounds, with regard to the thermal behavior study in a dynamic air atmosphere.

Aplica����o de Al-PILC na adsor����o de Cu2+, Ni2+e Co2+ utilizando modelos f��sico-qu��micos de adsor����o

Amostra de esmectita pertencente a Serra de Maicuru (Estado do Par��, Norte do Brasil, regi��o amaz��nica) foi pilarizada com Al13, A Argila pilarizada com alum��nio (Al-PILC) foi caracterizada por DRX, MEV e EDS. Para a an��lise textural foram utilizadas isotermas de adsor����o-desor����o utilizando o nitrog��nio. Este artigo �� dirigido ao estudo da adsor����o de metais pesados. A adsor����o dos ��ons de Cu2+, Ni2+e Co2+ foi realizadas com a matriz Al-PILC em temperatura ambiente com solu����es aquosas contendo os ��ons met��licos. Os modelos de adsor����o adotados foram os de Langmuir, Freundlich e Temkin que foram aplicados aos valores obtidos experimentalmente com regress��o linear. A equa����o de Langmuir foi o melhor modelo de lineariza����o com r = 0,999. A equa����o de Freundlich apresentou limita����es em altas concentra����es, mas foram obtidos valores (Kf e n) bastante aceit��veis utilizando este modelo. Os par��metros foram utilizados para calcular a quantidade de Nf em fun����o de Cs.

Thermal decomposition of solid state compounds of lanthanide and yttrium benzoates in CO2 atmosphere

Solid-state Ln-Bz compounds, where Ln stands for trivalent lanthanides and Bz is benzoate have been synthesized. Simultaneous thermogravimetric and differential thermal analysis in a CO2 atmosphere were used to study the thermal decomposition of these compounds.

A pH optode based on thymol blue: application to determination of CO2 using flow injection analysis system

An optode based on thymol blue (TB), an acid-based indicator, has been constructed and evaluated as a detector in FIA system for CO2 determination. The dye was chemically immobilised on the surface of a bifurcated glass optical fibre bundle, using silanisation in organic media. In FIA system, hydrogen carbonate or carbonate samples are injected in a buffer carrier solution, and then are mixed with phosphoric acid solution to generate CO2, which diffuses through a PTFE membrane, in order to be collected in an acceptor carrier fluid, pumped towards to detection cell, in which the optode was adapted. The proposed system presents two linear response ranges, from 1.0 x 10-3 to 1.0 x 10-2 mol l-1, and from 2.0 x 10-2 to 0.10 mol l-1. The sampling frequency was 11 sample h-1, with good repeatability (R.S.D < 4 %, n = 10). In flow conditions the optode lifetime was 170 h. The system was applied in the analysis of commercial mineral water and the results obtained in the hydrogen carbonate determination did not differ significantly from those obtained by potentiometry, at a confidence level of 95 %.

Synthesis, characterization and thermal behaviour of solid 2-methoxycinnamylidenepyruvate of some bivalent metal ions in CO2 and N2 atmospheres

Solid State M-2-MeO-CP compounds, where M stands for bivalent metals (Mn, Fe, Co, Ni, Cu and Zn) and 2-MeO-CP is 2-methoxycinnamylidenepyruvate, were synthesized. Simultaneous thermogravimetry and differential thermal analysis (TG-DTA), differential scanning calorimetry (DSC), elemental analysis and complexometry were used to establish the stoichiometry and to study the thermal behaviour of these compounds in CO2 and N2 atmospheres. The results were consistent with the general formula: M(L)2&#8729;H2O. In both atmospheres (CO2, N2) the thermal decomposition occurs in consecutive steps which are characteristic of each compound. For CO2 atmosphere the final residues were: Mn3O4, Fe3O4, Co3O4, NiO, Cu2O and ZnO, while under N2 atmosphere the thermal decomposition is still observed at 1000 �� C.

Thermal behaviour of succinic acid, sodium succinate and its compounds with some bivalent transitions metal ions in dynamic N2 and CO2 atmospheres

Thermal stability and thermal decomposition of succinic acid, sodium succinate and its compounds with Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II) were investigated employing simultaneous thermogravimetry and differential thermal analysis (TG-DTA) in nitrogen and carbon dioxide atmospheres and TG-FTIR in nitrogen atmosphere. On heating, in both atmospheres the succinic acid melt and evaporate, while for the sodium succinate the thermal decomposition occurs with the formation of sodium carbonate. For the transition metal succinates the final residue up to 1180 ��C in N2 atmosphere was a mixture of metal and metal oxide in no simple stoichiometric relation, except for Zn compound, where the residue was a small quantity of carbonaceous residue. For the CO2 atmosphere the final residue up to 980 ��C was: MnO, Fe3O4, CoO, ZnO and mixtures of Ni, NiO and Cu, Cu2O.

Kulutuster��ksen CO2-laserleikkaus

Kandidaatinty�� jakaantuu kirjalliseen ja kokeelliseen osaan. Kirjallisessa katsauksessa k��sitell����n teoriaa erityisesti laserleikkausprosesseja, resonaattorivaihtoehtoja, laserleikkausparametreja, laserleikkauksen etuja ja haittoja sek�� kulutuster��ksi��. Ty��n kokeellisessa osassa k��sitell����n kulutuster��ksen Raex 500 laserleikkausta nelj��lle eri pinnanlaadulle ainevahvuuden ollessa 12 mm.

Novel CO2 Regulated Proteins in Synechocystis PCC 6803

The large biodiversity of cyanobacteria together with the increasing genomics and proteomics metadata provide novel information for finding new commercially valuable metabolites. With the advent of global warming, there is growing interest in the processes that results in efficient CO2 capture through the use of photosynthetic microorganisms such as cyanobacteria. This requires a detailed knowledge of how cyanobacteria respond to the ambient CO2. My study was aimed at understanding the changes in the protein profile of the model organism, <i>Synechocystis</i> PCC 6803 towards the varying CO₂ level. In order to achieve this goal I have employed modern proteomics tools such as iTRAQ and DIGE, recombinant DNA techniques to construct different mutants in cyanobacteria and biophysical methods to study the photosynthetic properties. The proteomics study revealed several novel proteins, apart from the well characterized proteins involved in carbon concentrating mechanisms (CCMs), that were upregulated upon shift of the cells from high CO₂ concentration (3%) to that in air level (0.039%). The unknown proteins, Slr0006 and flavodiiron proteins (FDPs) Sll0217-Flv4 and Sll0219-Flv2, were selected for further characterization. Although <i>slr0006</i> was substantially upregulated under C_i limiting conditions, inactivation of the gene did not result in any visual phenotype under various environmental conditions indicating that this protein is not essential for cell survival. However, quantitative proteomics showed the induction of novel plasmid and chromosome encoded proteins in deltaslr0006 under air level CO₂ conditions. The expression of the <i>slr0006</i> gene was found to be strictly dependent on active photosynthetic electron transfer. Slr0006 contains conserved dsRNA binding domain that belongs to the Sua5/YrdC/YciO protein family. Structural modelling of Slr0006 showed an alpha/beta twisted open-sheet structure and a positively charged cavity, indicating a possible binding site for RNA. The 3D model and the co-localization of Slr0006 with ribosomal subunits suggest that it might play a role in translation or ribosome biogenesis. On the other hand, deletions in the <i>sll0217-sll218- sll0219</i> operon resulted in enhanced photodamage of PSII and distorted energy transfer from phycobilisome (PBS) to PSII, suggesting a dynamic photoprotection role of the operon. Constructed homology models also suggest efficient electron transfer in heterodimeric Flv2/Flv4, apparently involved in PSII photoprotection. Both Slr0006 and FDPs exhibited several common features, including negative regulation by NdhR and ambiguous cellular localization when subjected to different concentrations of divalent ions. This strong association with the membranes remained undisturbed even in the presence of detergent or high salt. My finding brings ample information on three novel proteins and their functions towards carbon limitation. Nevertheless, many pathways and related proteins remain unexplored. The comprehensive understanding of the acclimation processes in cyanobacteria towards varying environmental CO₂ levels will help to uncover adaptive mechanisms in other organisms, including higher plants.

Taxa de emiss��o de CO2 de um latossolo fertirrigado com ��cido fosf��rico por gotejamento

A aplica����o de fertilizantes fosfatados por meio de fertirriga����o com sistemas de irriga����o localizada pode causar obstru����o de emissores. Para evitar esse problema, pode ser utilizado o ��cido fosf��rico como fonte de f��sforo ��s plantas. Por��m, t��m sido pouco investigados os efeitos da irriga����o relacionados ��s perdas de CO2 do solo para a atmosfera, em conseq����ncia da decomposi����o do carbono org��nico e da infiltra����o de ��gua no solo. Neste trabalho, investigou-se, no per��odo de um m��s, o efeito da fertirriga����o com ��cido fosf��rico nas taxas de emiss��o de CO2 de um latossolo desprovido de vegeta����o, na ��rea Experimental de Irriga����o da UNESP, C��mpus de Jaboticabal - SP. Utilizou-se de um sistema de irriga����o por gotejamento, com delineamento experimental em blocos casualizados, constando de cinco repeti����es e cinco tratamentos (0; 30; 60; 90 e 120 kg ha-1de P2O5), aplicados via fertirriga����o com ��cido fosf��rico. Verificou-se que as taxas de emiss��o de CO2 aumentaram significativamente ap��s as fertirriga����es, por��m n��o houve efeito da dose do ��cido fosf��rico sobre as taxas. A umidade do solo mostrou-se um fator importante na rela����o entre as varia����es das taxas de emiss��o e a temperatura do solo ao longo do per��odo estudado.

Variabilidade espacial da emiss��o de CO2 em Latossolos sob cultivo de cana-de-a����car em diferentes sistemas de manejo

Neste trabalho, foi determinada a estrutura da variabilidade espacial da emiss��o de CO2, temperatura e umidade de solos desprovidos de vegeta����o em duas localidades sob cultivo da cana-de-a����car, em sistemas de manejos de cana crua e de cana queimada, no nordeste do Estado de S��o Paulo. A emiss��o de CO2 e a temperatura do solo foram registradas utilizando-se de c��mara de fluxo port��til e sensor de temperatura do sistema LI-6400. A umidade foi avaliada utilizando sistema port��til TDR. A maior emiss��o foi observada no local sob manejo de cana queimada, com valor m��dio de 2,05 &#956;mol m-2 s-1, por��m a depend��ncia espacial na emiss��o de CO2 foi encontrada somente na ��rea sob manejo de cana crua. Os mapas de krigagem da emiss��o de CO2, temperatura e umidade do solo sob manejo de cana queimada mostraram correspond��ncia �� declividade do terreno, com as maiores emiss��es e temperaturas localizadas na parte mais alta, sendo as maiores umidades do solo encontradas na parte mais baixa do local estudado. Os resultados indicam correla����o linear positiva da emiss��o de CO2 com a temperatura, e negativa com a umidade do solo somente no local com manejo de cana queimada, e n��o no sistema de cana crua, onde a presen��a de palhada certamente impede a a����o direta da radia����o solar e o escoamento de chuvas.

Carbonation of Mg(OH)2 in a pressurised fluidised bed for CO2 sequestration

I takt med den ekonomiska tillv��xten har CO2-utsl��ppen till atmosf��ren st��ndigt ��kat, och utan kraftiga ��tg��rder kommer de att forts��tta att ��ka i allt snabbare takt. Konsekvenserna av en p��tagligt f��rh��jd atmosf��risk CO2-halt ��r fortfarande os��kra (men eventuellt katastrofala) och fenomenet g��r under namnet global uppv��rmning eller klimatf��r��ndring. CCS fr��n engelskans ���carbon dioxide capture and storage��� framst��r som ett alternativ f��r att bek��mpa de st��ndigt ��kande CO2-utsl��ppen. Ett av de mer intressanta, och f��r Finlands del ��nda CCS-alternativet, baserar sig p�� naturens egna s��tt att begr��nsa atmosf��risk CO2, n��mligen vittring. Naturlig vittring, som f��renklat innefattar nedbrytningen av sten/berg (��ven k��nd som erosion) och de d��rp�� f��ljande reaktionerna med CO2-m��ttat regnvatten. Slutresultatet ��r en utf��llning av fasta mineraler som nu bundit CO2 i form av kalcium- och magnesiumkarbonat. Kalciumkarbonat ��r ��ven b��ttre k��nt som kalksten, d.v.s. CO2 blir bundet i sten. Det g��ller dock att snabba upp denna process, som i naturen ��r ytterst l��ngsam, p�� ett ekonomiskt och milj��m��ssigt h��llbart s��tt. Hittills har ett antal metoder f��r att p��skynda naturlig vittring, eller med andra ord ��ka CO2-upptagningsf��rm��gan av olika mineraler f��reslagits. De mera etablerade uttrycken (l��nade fr��n engelskan) talar om mineralkarbonatisering och CO2-mineralisering. Till skillnad fr��n m��nga andra CO2-mineraliseringsalternativ ��r det alternativ som behandlas i denna avhandling i h��g grad baserat p�� m��jligheten att utnyttja den v��rme som frig��rs vid karbonatisering. I teorin ��r det m��jligt att f��rest��lla sig en mineraliseringsprocess som inte kr��ver extern energi, men tillsvidare har man dock inte lyckats uppn�� detta m��l. Den process som presenteras i denna avhandling g��r ut p�� att man utvinner magnesium ur i naturen vanligt f��rekommande magnesiumrika mineraler, konverterar det till magnesiumhydroxid och d��refter karbonatiserar det till magnesiumkarbonat. I r��tta f��rh��llanden kan magnesiumhydroxid reagera med CO2 mycket snabbt och i nul��get har processen potential att minska CO2-utsl��ppen fr��n industri d��r spillv��rme finns till f��rfogande (t.ex. cement- och st��lindustrin). Fortsatt forskning ��r dock ett m��ste f��r att kunna p��verka CO2-utsl��ppen i en globalt signifikant skala.

Temporal variability of soil CO2 emission after conventional and reduced tillage described by an exponential decay in time model

To study Assessing the impact of tillage practices on soil carbon losses dependents it is necessary to describe the temporal variability of soil CO2 emission after tillage. It has been argued that large amounts of CO2 emitted after tillage may serve as an indicator for longer-term changes in soil carbon stocks. Here we present a two-step function model based on soil temperature and soil moisture including an exponential decay in time component that is efficient in fitting intermediate-term emission after disk plow followed by a leveling harrow (conventional), and chisel plow coupled with a roller for clod breaking (reduced) tillage. Emission after reduced tillage was described using a non-linear estimator with determination coefficient (R��) as high as 0.98. Results indicate that when emission after tillage is addressed it is important to consider an exponential decay in time in order to predict the impact of tillage in short-term emissions.